Researchers put a group of adults on a light diet for two years. All started with an ideal weight or were overweight but not obese.
At the end of the US study, they had lost 16.7lb on average and their sleep, health, sex drive and relationships all improved.
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All those consuming fewer calories had an improved health span
Another group who ate their normal diet lost less than 1lb in two years.
All those consuming fewer calories had an improved health span - the length of time free of disease.
The findings suggested calorie restriction should be seen as a vital tool in helping keep people healthy and happy, said Dr Corby Martin at Pennington Biomedical Research Centre, Louisiana.
Restricting calories was already known to help some species live longer but until now there have been fears it could harm humans.
The new findings were published by JAMA Internal Medicine.